﻿// Copyright 2006 - Ricardo Stuven (rstuven@gmail.com)
//
// This file is part of MsSqlSpatial.
// MsSqlSpatial is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
// 
// MsSqlSpatial is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Lesser General Public License for more details.

// You should have received a copy of the GNU Lesser General Public License
// along with MsSqlSpatial; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 

using System;
using System.IO;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlTypes;
using Microsoft.SqlServer.Server;
using MsSqlSpatial;
using Aggregate = MsSqlSpatial.Aggregate<GeoAPI.Geometries.IGeometry>;
using GeoAPI.Geometries;

[Serializable]
[SqlUserDefinedAggregate(Format.UserDefined
	, IsInvariantToNulls = true
	, IsInvariantToDuplicates = true
	, IsInvariantToOrder = true
	, IsNullIfEmpty = false
	, MaxByteSize = 8000
	)]
public struct UnionAggregate : IBinarySerialize
{
	[NonSerialized]
	private string cacheKey;
	[NonSerialized]
	private IGeometry aggregate;

	public void Init()
	{
		Aggregate.Initialize(out cacheKey, out this.aggregate);
	}

	public void Accumulate(SqlBytes ewkb)
	{
		IGeometry geometry = ConvertGeometry.ToGeometry(ewkb);
		if (geometry != null)
		{
			if (this.aggregate != null)
			{
				this.aggregate = geometry.Union(this.aggregate);
				this.aggregate.SRID = geometry.SRID;
			}
			else
			{
				this.aggregate = geometry;
			}
		}
	}

	public void Merge(UnionAggregate Group)
	{
		if (Group.aggregate != null)
		{
			this.aggregate = this.aggregate.Union(Group.aggregate);
			this.aggregate.SRID = Group.aggregate.SRID;
		}
	}

	public SqlBytes Terminate()
	{
		return ConvertGeometry.ToSqlBytes(Aggregate.Terminate(cacheKey));
	}

	#region IBinarySerialize Members

	public void Read(BinaryReader r)
	{
		Aggregate.Read(r, out cacheKey, out aggregate);
	}

	public void Write(BinaryWriter w)
	{
		Aggregate.Write(w, cacheKey, aggregate);
	}

	#endregion
}
